Evaluation of the NASA Modern Era Reanalysis for Research and Applications, Version-2 (MERRA-2)

The NASA Modern Era Reanalysis for Research Applications Version-2 (MERRA-2) provides an ongoing near-real time climate analysis beginning with the dawn of the modern satellite era in the late 1970's. While addressing known limitations of the now-completed MERRA reanalysis, MERRA-2 is primarily intended to be a development milestone for a future full Earth system reanalysis currently under development at GMAO. Among the advances in MERRA-2 toward the latter goal are the assimilation of interactive aerosols, improved representation of the stratosphere including ozone, and improved representations of cryospheric processes. This talk provides an overview of the MERRA-2 system developments and key results from a wide-ranging evaluation of the 35-year MERRA-2 product record to date. Important improvements in the quality of MERRA-2 compared with MERRA include the reduction of spurious trends and jumps related to changes in the observing system, and reduced biases and imbalances in the water cycle. Unresolved, and in some cases exacerbated, deficiencies are found in aspects of the global energy balance and in the assimilation of some observational data types.